1. Field of the Invention
The invention relates generally to printing devices, and, more particularly, to a drive apparatus in a printing device for driving media sheets in the printing device.
2. Description of the Related Art
Printing devices commonly referred to as printers, are widely used in offices, in homes and in business enterprises. The printing devices output information displayed on a screen of a data processing device onto a media sheet such as a sheet of paper. The printing devices as used herein may encompass printing systems such as color and black-and-white copiers, color and black-and-white printing systems, and so-called ‘all-in-one devices’ that incorporate multiple functions such as scanning, copying, and printing capabilities in one device. The term output as used herein may encompass any printed or digital form of text, graphic, or combination thereof.
The printing devices may be configured to suit a variety of applications. For instance, an application being executed on the data processing device may desire printing of the information on only one-side (simplex printing) of the media sheet while another application may desire printing of the information on both sides (duplex printing) of the media sheet. The printing devices may accordingly be configured to provide such output. Typically, for duplex printing, most of the printing devices follow a procedure of printing a first side of a media sheet in a printing region of a media path and partially exiting the media sheet from the media path while retaining at least a portion of the media sheet at an exit nip with the help of exit rolls. Thereafter, the direction of rotation of the exit rolls is reversed and the media sheet is inserted back into the media path of a printing device to perform the printing on a second side of the media sheet. Further, the media sheet is exited from the exit nip into an output bin of the printing device after completion of printing on both sides of the media sheet. The above printing operation may be referred to as a ‘peek-a-boo type of duplex turnaround printing’ as a portion of the media sheet is partially exited from the printing device and turned around by re-inserting in the printing device in order to print the second side of the media sheet.
Configuring the printing device for duplex printing requires a complex mechanism of gears for driving the media sheet in one-direction and then reversing direction of the exit rolls for driving the media sheet back along the media path, referred to as a redrive path, in the printing device. In addition to motors which drive the media sheet, such as a fuser motor, a duplexer motor and the like, a dedicated actuator such as a motor or a solenoid is typically used for reversing the direction of the exit rolls for driving the media sheet back along the redrive path in the printing device. Using the dedicated actuator increases cost, noise and power consumption of the printing device.
Further, if the duplexer motor is used to drive the exit rolls, it is held in operation even during simplex printing of the media sheet resulting in an increase in cost of operation along with an increase in noise and power consumption of the printing device. Furthermore, existing printing devices, which drive the exit rolls with the duplexer motor, preclude provisions for autonomy for the duplexer motor for driving the media sheet back along the redrive path in the printing device.
Based on the foregoing, there is a need for a printing device that precludes the need of a dedicated actuator for reversing the direction of the exit rolls for driving the media sheet back along the redrive path in the printing device. Further, the printing device should permit the duplexer motor to participate in driving the exit rolls without having to drive the exit rolls during simplex printing of the media sheet. Furthermore, the printing device should permit the duplexer motor autonomy to drive the media sheet back along the redrive path in the printing device, thereby allowing the duplexer motor to vary speed of the media sheet in redrive into the printing device.